<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
    </head>
    <body>
        <script>
            const words = ["hello", "apple", "common", "complete"];
            let a = [];
            function findWords(arr, key) {
                for (let i = 0; i < words.length; i++) {
                    if (arr[i].indexOf(key) !== -1) {
                        a.push(arr[i]);
                    }
                }
                return a;
            }
            console.log(findWords(words, "co"));
        </script>
    </body>
</html>
